I would go with Chief38 suggestion with lead shot. With steel shot, you would need to go two shot size smaller. But considering you are hunting on a private game farm, lead should be okay. I would verify it with the owner first. I would also use I/C on first barrel and mod in second. Pen raised birds are relative easy to bring down and will normally sit for the dog.
A few suggestions. How many shells you bring will depend upon how well you're shooting, at the moment. We are in the middle of pheasant season here (going hunting tomorrow). In the beginning of the season, I will hit perhaps 1 of every 3 birds (if I'm lucky). Now, with enough bird contacts, I'm shooting 3 of every 4 birds. You can avoid all this by practicing clay shooting, specifically, skeet.
Find someone to teach you how to shoot skeet at the range. There is always someone who will want to show off their skills. Very simply, you want to lean into the shot, twist at the waist, lead the target and continue after the shot. One good advice: it's like sweeping (keep barrel moving) the target out of the sky. When hunting, just slow it down.
Dogs. With a pointer, walk in on a point at a 45 degree angle to the dog (so the dog can see you). The dog is suppose to stay on point. Let the handler give the dog commands. That's one thing that gets owners/handlers hot, trying to command their dogs. You job is to flush the bird. With flushers, just make sure you don't shoot the dog.
With pen raised birds, they will normally run for any kind of cover, hedgerows, stands, corn fields, etc. I find that in early morning, they will be on the edges, trying to dry out yet close to cover. If you are hunting without dogs, then hunts will be different. Birds will run. Some will circle around you, those you can kick up by stopping so often. But you can push birds towards edges where a well placed someone can kick them up.
Pheasant or any upland bird hunting is a blast. You can't have enough shells. If they have dogs to rent, then by all means go for it. Good luck and have fun.